The invention relates to a rotatable or tiltable metallurgical vessel, in particular a pig iron mixer, having two raceways fastened, at a distance from each other, to the jacket of the metallurgical vessel, one raceway is mounted in a fixed bearing and the other is in an expansion bearing. A toothed element is arranged on the vessel jacket between the raceways, with which toothed element a driven counter-element engages.
Known pig iron mixers of this kind are mounted with their raceways on rollers, the rollers being guided by means of cages movable between the base and the raceways. In order to reach a synchronous movement of the rollers on the fixed-bearing side with those of the expansion-bearing side, i.e. in order to prevent slanting or moving of the pig iron mixer to one side, the cages of the expansion bearing and the fixed bearing have to be interconnected by transverse connections extending parallel to the longitudinal axis of the vessel. A plurality of X-shaped braces have been used for those connections. Despite those braces it has not been possible in practice to obtain completely synchronous running of the rollers of the expansion bearing with those of the fixed bearing, since, due to differences in lubrication and thermal stresses during charging and discharging as well as unequal friction conditions, relative movements between the rollers of the fixed bearing and those of the expansion bearing cannot be totally excluded. A play has always been present between the roller cages and the rollers, so that slanting of the rollers, and thus moving and slanting of the vessel, is inevitable despite the transverse braces. Slanting of the vessel and of the rollers in this case can lead to self-stoppage of the rollers, so that the vessel cannot be moved by means of its tilting drive any more. Due to the line contact of the rollers with the raceways, a vessel once slanted cannot slide back into its normal position by itself. It happens in fact that, with pig iron mixers mounted on rollers, the vessel slants considerably during a period of several months and has to be pressed back into its normal position by means of huge hydraulic presses.
The transverse braces interconnecting the cages and carrying out the movements of the cages which move at half angle speed compared to the pig iron mixer, make it impossible to accommodate the drive elements for the tilting movement below the vessel, i.e. within the vertical projection of the contours of the vessel. The drive elements--e.g. a pinion engaging with a toothed track extending about the periphery of the vessel, or a toothed rack linked to the jacket of the pig iron mixer--have to be provided laterally of the vessel, thus reducing the space around the vessel and complicating its accessibility. In particular access is low for pig iron mixers that have a separate charge opening and a discharge lip in which charging and discharging take place in the tilting counterdirection. Arranging drive elements beside the vessel therefore is undesirable and efforts have been made to accommodate the drive below the vessel, which efforts have not been satisfactorily effected so far. The known roller mountings--in addition to the question of the accessibility to the pig iron mixer and the great space needed for the drive--have also the disadvantage that both on the side of the base and on that of the pig iron mixer, very heavy bearings and supporting constructions, respectively, are necessary for the raceways of the rollers.